diff --git a/features/FEATURE_COMMON_PAL/mbed-coap/CHANGELOG.md b/features/FEATURE_COMMON_PAL/mbed-coap/CHANGELOG.md
index 7995a1d87a8..15d9feb4ffb 100644
--- a/features/FEATURE_COMMON_PAL/mbed-coap/CHANGELOG.md
+++ b/features/FEATURE_COMMON_PAL/mbed-coap/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Change Log
 
+## [v4.0.9](https://github.com/ARMmbed/mbed-coap/releases/tag/v4.0.9) 
+
+-[Full Changelog](https://github.com/ARMmbed/mbed-coap/compare/v4.0.8...v4.0.9)
+
+ **Closed issues:**
+  -  IOTCLT-1899 Maximum COAP message resending buffer size limited to 255 bytes
+  -  IOTCLT-1888 Problem with blockwise transfers that are even increments of block_size
+
 ## [v4.0.8](https://github.com/ARMmbed/mbed-coap/releases/tag/v4.0.8) 
 
 -[Full Changelog](https://github.com/ARMmbed/mbed-coap/compare/v4.0.4...v4.0.8)
diff --git a/features/FEATURE_COMMON_PAL/mbed-coap/module.json b/features/FEATURE_COMMON_PAL/mbed-coap/module.json
index df17fbba504..ec1ee8fb243 100644
--- a/features/FEATURE_COMMON_PAL/mbed-coap/module.json
+++ b/features/FEATURE_COMMON_PAL/mbed-coap/module.json
@@ -1,6 +1,6 @@
 {
   "name": "mbed-coap",
-  "version": "4.0.8",
+  "version": "4.0.9",
   "description": "COAP library",
   "keywords": [
     "coap",
diff --git a/features/FEATURE_COMMON_PAL/mbed-coap/source/include/sn_coap_protocol_internal.h b/features/FEATURE_COMMON_PAL/mbed-coap/source/include/sn_coap_protocol_internal.h
index 3a603d3dfa4..19f057f2789 100644
--- a/features/FEATURE_COMMON_PAL/mbed-coap/source/include/sn_coap_protocol_internal.h
+++ b/features/FEATURE_COMMON_PAL/mbed-coap/source/include/sn_coap_protocol_internal.h
@@ -225,7 +225,7 @@ struct coap_s {
     uint32_t system_time;    /* System time seconds */
     uint16_t sn_coap_block_data_size;
     uint8_t sn_coap_resending_queue_msgs;
-    uint8_t sn_coap_resending_queue_bytes;
+    uint32_t sn_coap_resending_queue_bytes;
     uint8_t sn_coap_resending_count;
     uint8_t sn_coap_resending_intervall;
     uint8_t sn_coap_duplication_buffer_size;
diff --git a/features/FEATURE_COMMON_PAL/mbed-coap/source/sn_coap_protocol.c b/features/FEATURE_COMMON_PAL/mbed-coap/source/sn_coap_protocol.c
index aed99fb242b..a0660e6ee42 100644
--- a/features/FEATURE_COMMON_PAL/mbed-coap/source/sn_coap_protocol.c
+++ b/features/FEATURE_COMMON_PAL/mbed-coap/source/sn_coap_protocol.c
@@ -2027,7 +2027,7 @@ static sn_coap_hdr_s *sn_coap_handle_blockwise_message(struct coap_s *handle, sn
                 original_payload_len = stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len;
                 original_payload_ptr = stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr;
 
-                if ((block_size * (block_number + 1)) > stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len) {
+                if ((block_size * (block_number + 1)) >= stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len) {
                     src_coap_blockwise_ack_msg_ptr->payload_len = stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len - (block_size * block_number);
                     src_coap_blockwise_ack_msg_ptr->payload_ptr = stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr + (block_size * block_number);
                 }
@@ -2080,7 +2080,7 @@ static sn_coap_hdr_s *sn_coap_handle_blockwise_message(struct coap_s *handle, sn
                 stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len = original_payload_len;
                 stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_ptr = original_payload_ptr;
 
-                if ((block_size * (block_number + 1)) > stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len) {
+                if ((block_size * (block_number + 1)) >= stored_blockwise_msg_temp_ptr->coap_msg_ptr->payload_len) {
                     sn_coap_protocol_linked_list_blockwise_msg_remove(handle, stored_blockwise_msg_temp_ptr);
                 }